Peterson: Material Discovered in Uinta Basin. 69 



A partial cast of the brain-case indicates a fairly large-sized brain. 

 The lower jaw is well proportioned, there being considerable depth to 

 the ramus throughout. The symphysis is quite strong and extends 

 back opposite P-. 



From the study of the upper dentition alone one would perhaps 

 hesitate in referring the Uinta remains to a separate genus. Thus 

 the roots of the superior canines, which are still in position, reveal just 

 such a powerful and recurved apex as is indicated in Sinclair's illus- 

 tration. P-, which however is separated by a short diastema from 

 P-, is larger than the preceding tooth, and has a more gentle slope of 

 the posterior border; otherwise there is little or no difference between 

 the two. P- agrees with the description and illustration by Sinclair 

 just referred to, except that the deuterocone is somewhat better 

 developed. P- appears to have the cingulum very little, if at all, 

 developed; the antero- and protero-external cus- 

 pules are absent; nevertheless on the whole the 

 tooth closely resembles that of the specimen of 

 Homacodon described by Sinclair. The most pro- 

 nounced modification of the molars is the union 

 into a cross-crest of the antero-internal and me- 

 dian tubercles, which is especially well accom- 

 plished on M- and M- of the type, but which 

 cannot be said to have taken on an advanced 

 selenodont pattern, as is seen in Bimomeryx Wort- 

 man.28 On the contrary these crests are very Fig. 9. Hylomeryx 



, , ... . , , ... • 1- • r annectens. Carnegie 



penssodactyl-like with the slightest indication 01 ,^ 



, , Museum No. 2944. 



the intermediate tubercle on an unworn or x i i I2. 

 slightly worn tooth, (see Fig. 9, M- and M-). 



This condition is quite clearly foreshadowed in Homacodon where the 

 intermediate closely crowds the antero-internal tubercle. 



When the study and comparison of the inferior dentition is taken 

 up, it is clear that a considerable modification toward the selenodont 

 pattern of the tooth-structure has taken place in these Uinta remains, 

 which at once separates them from the Bridger form. In the paratype, 

 No. 2944, both rami are preserved (the left with the symphysis com- 

 plete), containing two incisors represented by moderately large 

 roots subequal in size.-^ The canine is a large trenchant tooth with 



^^ Bull. Amer. Mus. Nat. Hist., Vol. X, 1898, p. 100, Fig. 2. 



25 Unfortunately there are as yet no incisors known in Homacodon, but I judge 

 that genus to have two, as in the present form. 



